Citations

AbstractObjectiveTo describe video‐assisted microwave ablation (VAMA) for the treatment of a metastatic lung lesion secondary to right forelimb osteosarcoma in a dog.Study designCase report.AnimalsA 10‐year‐old female spayed mixed breed dog with a metastatic lung lesion secondary to appendicular osteosarcoma.MethodsAn osteosarcoma of the right distal scapula and proximal humerus that was suspected to be a radiation‐induced osteosarcoma was treated with limb amputation and carboplatin chemotherapy. The patient developed pulmonary metastatic lesions and hypertrophic osteopathy (HO). VAMA of a metastatic lesion in the right caudal lung lobe was performed 227 days after amputation. The procedure was performed without complication.ResultsFollow‐up information with the referring veterinarian 40 days after VAMA indicated that the patient was stable and that the clinical signs of HO had resolved. Thoracic radiographs taken by the referring veterinarian (RDVM) at monthly intervals showed that the previously treated metastatic lesion was stable. At 134 days from VAMA, the patient presented to the RDVM for lethargy and dyspnea and was transferred to an emergency clinic. The patient arrested and died 136 days from the VAMA procedure while hospitalized. A postmortem was not performed.ConclusionVAMA for pulmonary metastatic lesions is technically feasible and allows for the treatment of symptoms associated with HO and minimally invasive management of pulmonary metastases in the case reported.

LRRK2 mutations produce end-stage Parkinson’s disease (PD) with reduced nigrostriatal dopamine, whereas, asymptomatic carriers have increased dopamine turnover and altered brain connectivity. LRRK2 pathophysiology remains unclear, but reduced dopamine and mitochondrial abnormalities occur in aged G2019S mutant knock-in (GKI) mice. Conversely, cultured GKI neurons exhibit increased synaptic transmission. We assessed behavior and synaptic glutamate and dopamine function across a range of ages. Young GKI mice exhibit more vertical exploration, elevated glutamate and dopamine transmission, and aberrant D2-receptor responses. These phenomena decline with age, but are stable in littermates. In young GKI mice, dopamine transients are slower, independent of dopamine transporter (DAT), increasing the lifetime of extracellular dopamine. Slowing of dopamine transients is observed with age in littermates, suggesting premature ageing of dopamine synapses in GKI mice. Thus, GKI mice exhibit early, but declining, synaptic and behavioral phenotypes, making them amenable to investigation of early pathophysiological, and later parkinsonian-like, alterations. This model will prove valuable in efforts to develop neuroprotection for PD.

PurposeMicrodosimetry is a vital tool for assessing the microscopic patterns of energy deposition by radiation, which ultimately govern biological effect. Solid‐state, silicon‐on‐insulator microdosimeters offer an approach for making microdosimetric measurements with high spatial resolution (on the order of tens of micrometers). These high‐resolution, solid‐state microdosimeters may therefore play a useful role in characterizing proton radiotherapy fields, particularly for making highly resolved measurements within the Bragg peak region. In this work, we obtain microdosimetric measurements with a solid‐state microdosimeter (MicroPlus probe) in a clinical, spot‐scanning proton beam of small spot size.MethodsThe MicroPlus probe had a 3D single sensitive volume on top of silicon oxide. The sensitive volume had an active cross‐sectional area of 250 μm × 10 μm and thickness of 10 μm. The proton facility was a synchrotron‐based, spot‐scanning system with small spot size (σ ≈ 2 mm). We performed measurements with the clinical beam current (≈1 nA) and had no detected pulse pile‐up. Measurements were made in a water‐equivalent phantom in water‐equivalent depth (WED) increments of 0.25 mm or 1.0 mm along pristine Bragg peaks of energies 71.3 MeV and 159.9 MeV, respectively. For each depth, we measured lineal energy distributions and then calculated the dose‐weighted mean lineal energy, . The measurements were repeated for two field sizes: 4 × 4 cm2 and 20 × 20 cm2.ResultsFor both 71.3 MeV and 159.9 MeV and for both field sizes, increased with depth toward the distal edge of the Bragg peak, a result consistent with Monte Carlo calculations and measurements performed elsewhere. For the 71.3 MeV, 4 × 4 cm2 beam (range at 80% distal falloff, R80 = 3.99 cm), we measured keV/μm at WED = 2 cm, and keV/μm at WED = 3.95 cm. For the 71.3 MeV, 20 × 20 cm2 beam, we measured keV/μm at WED = 2.6 cm, and keV/μm at WED = 3 cm. For the 159.9 MeV, 4 × 4 cm2 beam (R80 = 17.7 cm), keV/μm at WED = 5 cm, and keV/μm at WED = 17.6 cm. For the 159.9 MeV, 20 × 20 cm2 beam, keV/μm at WED = 5 cm, and keV/μm at WED = 17.6 cm.ConclusionsWe performed microdosimetric measurements with a novel solid‐state, silicon‐on‐insulator microdosimeter in a clinical spot‐scanning proton beam of small spot size and unmodified beam current. For all of the proton field sizes and energies considered, the measurements of were in agreement with expected trends. Furthermore, we obtained measurements with a spatial resolution of 10 μm in the beam direction. This spatial resolution greatly exceeded that possible with a conventional gaseous tissue‐equivalent proportional counter and allowed us to perform a high‐resolution investigation within the Bragg peak region. The MicroPlus probe is therefore suitable for applications in proton radiotherapy.